Naturologie: Harmful plants, again

Summer brings warm weather, which in turn brings us outside and in contact with plants that may harm us. Generally these are the plants armed with hairs, barbs and prickles or those containing an irritant. Most of us in search of a raspberry or two remember the sharp pang of bristles and thorns. Raspberries, blackberries and dewberries are all armed with bristles that easily break off. The plants are so armed to keep herbivores from grazing. Roses too, have various kinds of prickles along their stems. Other plants contain stronger mechanisms to avoid consumption.

Stinging Nettles commonly seen along seashores, wharves or old livestock pens have stinging hairs along their stems. These are actually hollow, containing an acid that once it enters our skin causes a burning sensation. Nettle sting or burn can lasts minutes or hours depending on sensitivity. Yet these plants collected earlier, in spring, make a delicious potherb. Their leaves are often dried and even added to teas or cheese as flavouring.

“Leaflets three, let em be” is often heard in relation to Poison-ivy. Many plants have three leaflets, but poison-ivy is distinctive. Its leaflets have a shallow tooth towards their tips, and sometimes two. The plant is a woody vine, sprouting its greenish flowers beneath the leaves. The fruit is white upon maturity, appearing in clusters. Poison-ivy leaves turn beautiful variegated colours of pinks and purples in fall. The plants should not be handled, picked nor dug without protection in any season. All stems and leaves contain an irritating sap that causes painful burning and itchy blisters on sensitive individuals often needing medical attention. We have two very common species of poison-ivy, found along sandy seashores of the Northumberland Strait, along streams, lakeshores and in gypsum areas, throughout the province. Note: Plants should never be burned. The resulting smoke can cause permanent lung damage without proper equipment.

Seen in roadside ditches, shady paths and along streamside is the native Cow-parsnip or bugosi. Its sap also causes stinging, painful blisters with the added detriment of causing photosensitivity on affected areas that may last years. This means that sunlight on those areas may cause the return of blisters. Two closely related species of this wild plant are becoming invasive in our province, Hogweed and Giant Hogweed. Both introduced as garden plantings (via seeds) from Europe or Asia and both cause extreme rashes when we contact them. Most problematic are the leaves and stalks. These plants are proving to be tenacious and difficult to remove. We have not seen them on offshore islands, otherwise they are considered to be throughout Nova Scotia. In case you wonder how the original plants arrived without causing harm: they were probably planted from seeds, which contain no irritants. Closely related is Wild Parsnip, a yellow-flowered plant with similar leaves and causing similar effects on skin.

But take heart, out of 1600 species of plants, there are only about two dozen that cause us grief by touch, and enjoy our short summer! If you are wondering if your property may have harmful plants as listed above please contact me through this site or join us July 21 at 10:30AM and Ask a Curator your botanical questions. @NovaScotiaFlora #NSBotany